In an electronic device, there are cases where a noise generated from an electronic component propagates through a parallel flat plane that is formed by a power source-ground plane as a kind of a waveguide so as to have an adverse influence on the other electronic components, a wireless circuit located close thereto, or the like. Therefore, countermeasures for the noise are generally taken, and many techniques have been developed.
Recently, it has been disclosed that the propagation characteristics of electromagnetic waves can be controlled by periodically arranging a conductive body pattern having a specific structure. Particularly, a meta material configured so as to suppress the propagation of electromagnetic waves in a specific frequency band is called an electronic band gap structure (hereinafter, referred to as an EBG structure), and a countermeasure for noise using the EBG structure has attracted attention.
As a technique of such a type, for example, there is a technique described in Patent Document 1 (U.S. Pat. No. 6,262,495 Specification). In FIG. 2 of Patent Document 1, a structure, that is, a so-called EBG structure of a mushroom type is illustrated, in which a plurality of island-shaped conduction elements is arranged on the upper side of a sheet-shaped conduction plane, and each of the island-shaped conduction elements is connected to the conduction plane through a via.
In addition, as a technique of such a type, there is a technique disclosed in Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-253929). In FIG. 4 of Patent Document 2, an EBG structure that is configured by connecting two conductive bodies facing each other is illustrated. In addition, the inductance component of a conductive body that is formed in a lower level out of the two conductive bodies facing each other is increased by applying a conductive body pattern for which a large reflection coefficient is acquired in a Bragg frequency.